1. Field of the Invention
The present invention relates to a method and apparatus for the combustion or gasification of highly viscous and/or suspended fuel in a burner flame. The fuel is introduced, in a nozzle, and in the form of a continuous, thin, annular layer, into a stream of atomizing medium, with the aid of which the fuel is atomized.
2. Description of the Prior Art
One method of this general type is known from the "Fifth International Symposium on Coal Slurry Combustion and Technology", Tampa, Fla., April 1983, pages 625 et seq, especially FIG. IV on page 636. With this known way of carrying out the method, the fuel exiting in an annular layer is embraced by two similar annular atomizing airstreams, and exits an annular gap together with the airstreams, accompanied by a reduction of the thickness of the layer of the fuel. The heat shield that delimits the inner edge of this annular gap requires a special cooling. Furthermore, there exists the danger that as a result of instabilities the thin annular layer makes contact with the wall portions that delimit the annular gap, where it leads to increased wear. In addition, although the atomizing material exits the conical annular gap at a relatively slow speed, the atomizing air exits at a high, major resonant speed, so that the relatively slow speed of the atomizing material cannot be so slow that atomization occurs in the nozzle as a result of shearing forces. This known method yields a relatively poor atomization quality for the gasification or combustion, especially with regard to stabilization of the flame of low-caloric fuels. Furthermore, due to the necessary major resonant exit flow, when this known method is used for pressure gasification, a very high supply pressure of the nozzle must be provided for the atomizing medium.
An object of the present invention is to provide a method and apparatus for the combustion or gasification of liquid, highly viscous and/or suspended fuel, where a low wear of the material of the nozzle occurs, and the atomization can be effected at a relatively low supply pressure of the nozzle.